What does the term "Fugue" used by psychologists mean? in what way it is different from simple amnesia?

A fugue state is a sudden forgetfulness by a person that includes forgetting their identity of anything else about themselves. It is usually a reversible state and cannot be associated with the use of psychogenic substances. It usually involves travel or being lost somewhere. It differs from simple amnesia in the sense that it is always reversible at some point and has not necessarily been usually with any injury or assault to the head and does not necessarily involve any other loss of functioning.